JP2006126861A - Plastic optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a step index type plastic optical fiber that has large numerical apertures (NA), low transmission loss over a wide wavelength range, and small bending loss. <P>SOLUTION: In the step index type plastic optical fiber, the materials of a core and a cladding consist of amorphous fluororesin having substantially no hydrogen atom, and the core material uses amorphous fluororesin having lower refractive index than before, and/or as the clad material amorphous fluororesin having lower refractive index than before is used, thereby increasing the difference in refractive index between the both materials. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a step index type plastic optical fiber (hereinafter referred to as an SI type optical fiber), and more particularly to an SI type optical fiber capable of transmitting a wide range of light from the visible to the near infrared region and having a large numerical aperture.

  Conventional optical fibers have been mainly made of quartz, but plastic optical fibers have been developed and put into practical use in order to overcome poor processability and weakness against bending. A normal plastic optical fiber has a basic structural unit of a core made of a transparent resin such as polymethyl methacrylate and polycarbonate and a clad made of a resin such as a transparent fluoropolymer having a lower refractive index than that of the core.

However, these resin materials have overtone absorption of stretching vibration based on carbon-hydrogen bonds existing in the polymer, and transmission loss in the near infrared region is large. In order to solve this problem, studies have been made to reduce transmission loss in the near infrared region by introducing fluorine atoms instead of hydrogen atoms to eliminate carbon-hydrogen bonds. For example, Patent Document 1 describes an SI type optical fiber using a perfluoropolymer as a material for a core and a clad.
Japanese Patent No. 2821935

  A conventional plastic optical fiber using a perfluoropolymer for the core and the clad has a problem that the numerical aperture (NA) is small because the difference in refractive index between the core and the clad is small. The present invention solves this problem and provides a plastic optical fiber suitable for use in optical communication media such as various industrial and medical sensors that can receive a wide range of light with a small loss during bending. With the goal.

  The present invention comprises an amorphous fluororesin (A-1) composed of a fluoropolymer having a core substantially free of hydrogen atoms and having a chlorine atom in the side chain, wherein the cladding is substantially hydrogen atoms. This is an SI type optical fiber made of an amorphous fluororesin (B) composed of a fluorine-containing polymer not having a refractive index and having a refractive index difference between the core and the clad of 0.020 or more.

  In the present invention, the core is made of an amorphous fluororesin (A) composed of a fluorine-containing polymer containing a high refractive index agent and having substantially no hydrogen atom, and the clad is substantially a hydrogen atom. This is an SI type optical fiber made of an amorphous fluororesin (B) composed of a fluorine-containing polymer not having a refractive index and having a refractive index difference between the core and the clad of 0.020 or more.

  The present invention also comprises an amorphous fluororesin (A) comprising a fluoropolymer having a core substantially free of hydrogen atoms, or the amorphous fluororesin (A) containing a high refractive index agent. The clad is made of an amorphous fluororesin (B-2) composed of a fluoropolymer having a refractive index of less than 1.300 and substantially free of hydrogen atoms, and the difference in refractive index between the core and the clad is 0.020. This is the SI type optical fiber as described above.

Further, the present invention provides an amorphous fluororesin (A) having a core composed of a fluoropolymer having a repeating unit represented by the following formula (1) and having the monomer (a) cyclopolymerized: A monomer (b) comprising the amorphous fluororesin (A) containing a rater and having a clad represented by the following formula (4):
-1) an amorphous fluororesin (B-3) composed of a fluoropolymer having a polymerized repeating unit, or the amorphous fluororesin (B-3) containing a fluoroplasticizer having substantially no hydrogen atom 3), and is an SI type optical fiber having a refractive index difference between the core and the clad of 0.020 or more.

However, m is an integer of 0-5, R < ¹ >, R < ² >, R < ³ > and R < ⁴ > are each independently a C1-C9 perfluoroalkyl group, a chlorine atom or a fluorine atom, R < ¹³ > is C2-C9 A perfluoroalkyl group, R ¹⁴ represents a C 1-9 perfluoroalkyl group or a fluorine atom.

  The present invention also comprises an amorphous fluororesin (A) comprising a fluoropolymer having a core substantially free of hydrogen atoms, or the amorphous fluororesin (A) containing a high refractive index agent. Amorphous fluororesin (B) composed of a fluoropolymer whose clad has substantially no hydrogen atom, or the amorphous fluororesin (B) containing a fluoroplastic that has substantially no hydrogen atom And a numerical aperture (NA) of 0.415 or more.

  The present invention also relates to a fluoropolymer having perfluoro (2-pentyl-1,3-dioxole), a repeating unit obtained by polymerizing the perfluoro (2-pentyl-1,3-dioxole), and an optical member using the polymer.

  The SI type optical fiber of the present invention can increase the numerical aperture by increasing the refractive index difference between the core and the clad without reducing the light transmission performance. As a result, the transmission loss at the time of bending does not increase, and when used in a sensor or the like, the sensor sensitivity can be improved because light can be collected from a wide range. Moreover, a low level transmission loss can be given over a wide wavelength region of wavelengths of 600 to 1600 nm. That is, by using the same wavelength as the quartz optical fiber, it is easy to connect to the quartz optical fiber, and it is less expensive than a conventional plastic optical fiber that has to use a wavelength shorter than 600 to 1600 nm. There are benefits.

On the other hand, since the SI optical fiber of the present invention has a large fiber diameter and is easy to connect to a light source / light-receiving element or to each other, like an ordinary plastic optical fiber, an inexpensive short-range communication system can be constructed. Furthermore, since the SI type optical fiber of the present invention has drastically improved heat resistance compared to ordinary plastic optical fiber, it has high thermal stability and is exposed to a high temperature above room temperature for a long time. In this case, it is possible to prevent a reduction in transmission loss. Further, since the cladding can be made flexible, a fiber that hardly causes cracks can be obtained.

  The amorphous fluororesin in the present invention is composed of two or more kinds of specific fluoropolymers that become amorphous, and other constituent components other than the fluoropolymer Small amounts of additives may be included. Furthermore, the amorphous fluororesin may contain a small amount of a crystalline fluoropolymer (a fluoropolymer that becomes crystalline alone) as long as it is entirely amorphous.

  The specific fluorine-containing polymer is also a polymer having substantially no hydrogen atom. When another polymer other than the specific fluorine-containing polymer that becomes amorphous is used in combination, the other polymer is also a polymer having substantially no hydrogen atom. That is, the polymer constituting the amorphous fluororesin in the present invention is composed of a polymer having substantially no hydrogen atom. Unless otherwise specified, the polymer constituting the amorphous fluororesin means a substance having substantially no hydrogen atom. Hereinafter, the “polymer” may be either a homopolymer or a copolymer unless specifically referred to as “homopolymer” or “copolymer”.

  The SI optical fiber includes a core and a clad having a relatively low refractive index. As the refractive index difference between the core and the clad increases, the numerical aperture (NA) increases. Amorphous fluororesin is inherently a low refractive index resin, and when used as a core material, the range of selection of a cladding material that must have a lower refractive index is smaller than that, and the refractive index difference is increased. It was difficult to do. The present invention uses an amorphous fluororesin in the same category as that of the core as the cladding material, and increases the refractive index difference between the core and the cladding as compared with the prior art, and the optical properties and mechanical properties of each material. The purpose is to increase.

  One aspect of the present invention is to increase the refractive index of the core by using an amorphous fluororesin composed of a fluorine-containing polymer having a chlorine atom which has an effect of increasing the refractive index as a material of the core. This is to increase the rate difference. This chlorine atom must be a chlorine atom bonded to the side chain of the polymer, and if the chlorine atom is bonded to a carbon atom of the main chain, the polymerizability of the monomer is deteriorated and the polymer is stable. There is a problem that a high molecular weight substance having physical properties cannot be obtained, or that the crystallinity is increased and scattering loss is increased.

  In the present invention, the main chain of the fluoropolymer constituting the amorphous fluororesin consists of a chain of only carbon atoms, and the main chain is a chain of two carbon atoms constituting a polymerizable double bond. Formed from. In addition, in a polymer obtained by cyclopolymerization of a monomer having two polymerizable double bonds (hereinafter also referred to as fluorine-containing dienes), four carbon atoms constituting two polymerizable double bonds. A main chain is formed from the chain. Therefore, having a chlorine atom in the side chain means that it has no chlorine atom directly bonded to the carbon atoms constituting these polymerizable double bonds, but has a chlorine atom bonded to another carbon atom. To do.

  The present invention also increases the refractive index of the core and increases the refractive index difference from the cladding by using an amorphous fluororesin containing a high refractive index agent as the core material. This high refractive index agent is a compound having a higher refractive index than the fluorine-containing polymer constituting the blended amorphous fluororesin, and the refractive index of the amorphous fluororesin blended with it is blended. It has a higher refractive index than non-crystalline fluororesin. Usually, the refractive index of an amorphous fluororesin increases with the amount of the high refractive index agent. As the high refractive index agent, a fluorine-containing aromatic compound having substantially no hydrogen atom is particularly preferable.

  In the present invention, the difference in refractive index from the core is increased by using a fluoropolymer having a refractive index lower than that of the conventional fluoropolymer constituting the amorphous fluororesin of the clad. A polymer of perfluoro (2,2-dimethyl-1,3-dioxole) (the following formula (5), hereinafter referred to as PDD) is known as a fluorine-containing polymer constituting the amorphous fluororesin of the clad. In the present invention, a fluoropolymer having a lower refractive index is used.

  Two or more means for increasing the refractive index difference between the core and the clad can be combined. For example, a fluorine-containing polymer having a chlorine atom and a high refractive index agent are combined to form a core, and this core is combined with a clad made of a lower refractive index fluorine-containing polymer. For example, a core made of a crystalline fluororesin and a clad made of a fluoropolymer having a lower refractive index are combined.

  Furthermore, in the present invention, the clad can be made of an amorphous fluororesin containing a fluoroplasticizer. A low refractive index fluoropolymer as a cladding material is usually highly rigid and brittle, so it is preferable to add a plasticizer to increase flexibility. By forming the clad with a highly flexible material, it is possible to suppress the occurrence of cracks and the like when the SI type optical fiber is bent. The plasticizer is required to be a fluorine compound in order to increase the affinity with the fluorine-containing polymer, and preferably has substantially no hydrogen atom. When the fluorine-containing plasticizer is a compound having a high fluorine content, there is an effect of lowering the refractive index of the cladding.

  In the present invention, increasing the refractive index difference between the core and the clad, that is, increasing the numerical aperture (NA) suppresses an increase in transmission loss when the SI type optical fiber is bent. Since light can be condensed from a wide range, it is preferable that the sensor sensitivity can be improved.

  In order for the SI optical fiber of the present invention to achieve a sufficiently large numerical aperture, the refractive index difference between the core amorphous fluororesin and the clad amorphous fluororesin must be 0.020 or more. . The larger the refractive index difference, the higher the numerical aperture. The refractive index difference is preferably 0.030 or more, more preferably 0.040 or more, further preferably 0.045 or more, particularly preferably 0.050 or more, and most preferably 0. 0.060 or more. The upper limit of the refractive index difference is not particularly limited, but is usually 0.2.

  Based on this refractive index difference, the numerical aperture of the SI type optical fiber of the present invention is preferably 0.280 or more. More preferably, it is 0.325 or more, More preferably, it is 0.364 or more, Especially preferably, it is 0.380 or more, Most preferably, it is 0.415 or more. The upper limit of the numerical aperture is not particularly limited but is usually 0.75.

In order to increase the refractive index difference, a method using a core material having a higher refractive index than the conventional method, a method using a clad material having a lower refractive index than the conventional method, and a method using the conventional There is a method of combining a core material having a higher refractive index and a clad material having a lower refractive index than the conventional one, and the core amorphous fluororesin and the clad amorphous fluororesin in the present invention are either of these methods. It can also be applied to.

  The core amorphous fluororesin and the clad amorphous fluororesin in the present invention are amorphous fluororesins in the same category except that the refractive indexes are different. In order to distinguish the two, hereinafter, the core amorphous fluororesin is referred to as amorphous fluororesin (A), and the clad amorphous fluororesin is referred to as amorphous fluororesin (B).

  The fluorinated polymer constituting these amorphous fluororesins is a polymer that does not substantially have a hydrogen atom and does not have a carbon-hydrogen bond. Since the amorphous fluororesin is composed of a fluoropolymer that has substantially no hydrogen atoms, transmission loss in the near infrared region is reduced and light from visible light to near infrared light is improved. An SI-type optical fiber that can be transmitted is obtained. In addition, the fact that the fluororesin is amorphous reduces the scattering loss particularly in the short wavelength region of the SI type optical fiber.

  Further, the amorphous fluororesin may be composed only of a fluoropolymer, and may contain an additive as long as optical transmission performance, mechanical performance, etc. are not substantially impaired. Examples of the additive include a plasticizer, a refractive index adjuster, various stabilizers, and a crosslinking agent. These are preferably fluorine compounds having a high affinity for the fluorinated polymer in order not to substantially impair the optical transmission performance or to improve the performance. In particular, it is preferable to include a high refractive index agent as a refractive index adjusting agent in the core amorphous fluororesin (A) in order to increase the NA of the SI optical fiber. In addition, it is preferable to include a plasticizer in the amorphous fluororesin (B) of the cladding in order to give flexibility to the optical fiber.

  As the fluorinated polymer constituting the amorphous fluororesin in the present invention, a polymer having a repeating unit obtained by cyclopolymerizing a fluorinated diene (hereinafter also referred to as a cyclized polymer) and a fluorinated dioxole are polymerized. A polymer having a repeating unit (hereinafter also referred to as a dioxol polymer) is preferred. The cyclized polymer may be a copolymer of two or more fluorine-containing dienes, or may be a copolymer of a fluorine-containing diene and another copolymerizable monomer. As other copolymerizable monomers, polymerizable monoenes are suitable. The dioxole-based polymer may also be a copolymer of two or more fluorine-containing dioxoles, or a copolymer of a fluorine-containing dioxole and other copolymerizable monomers. Further, the fluorine-containing polymer constituting the amorphous fluorine resin may be a copolymer of fluorine-containing dienes and fluorine-containing dioxoles.

  Among the above fluoropolymers, the dioxole-based polymer tends to have a particularly low refractive index as compared with the cyclized polymer, so that the fluoropolymer constituting the clad amorphous fluororesin (B). Is preferably a dioxole polymer, and the fluorinated polymer constituting the core amorphous fluororesin (A) is preferably a cyclized polymer. Copolymers of fluorine-containing dienes and fluorine-containing dioxoles can be used for both the core and the clad due to the difference in refractive index from other amorphous fluoropolymers to be combined. It is.

  The polymer can be obtained using any of the known methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization using the monomers described below. In the polymerization, a radical generator is usually used as a polymerization initiator. After the polymerization, post-treatment such as fluorination of the obtained polymer can be performed in order to remove the unstable group at the polymer terminal.

The viscosity of the fluoropolymer in the molten state is preferably 1 × 10 ² to 1 × 10 ⁵ Pa · s at a melting temperature of 200 to 300 ° C. If the melt viscosity is too high, melt spinning becomes difficult. Moreover, even if melt viscosity is too low, it is not preferable practically. That is, when it is used as an optical transmission body in an electronic device, an automobile, etc., it softens at a high temperature and the transmission performance as an SI type optical fiber deteriorates.

The number average molecular weight M _n of the fluoropolymer is preferably 1 × 10 ^{4 to} 5 × 10 ^{6, and} more preferably 5 × 10 ⁴ to 1 × 10 ⁶ . If the molecular weight is too small, the heat resistance may be deteriorated, and if it is too large, the melt viscosity becomes high and molding becomes difficult.
Among the fluorinated polymers constituting the amorphous fluororesin, the cyclized polymer is a repeating unit obtained by cyclopolymerization of a monomer represented by the following formula (1) (hereinafter referred to as monomer (a)). The polymer which has is preferable.

However, m represents an integer of 0 to 5, and R ¹ , R ² , R ³ and R ⁴ each independently represents a C 1-9 perfluoroalkyl group, a chlorine atom or a fluorine atom. When m is 2 or more, a plurality of R ³ (same for R ⁴ ) may be different from each other. As m, an integer of 0 to 3 is particularly preferable.

As R ¹ , R ² , R ³ and R ⁴ , at most 3 are preferably a perfluoroalkyl group or a chlorine atom, and the other is preferably a fluorine atom. In particular, the monomer (a) having a perfluoroalkyl group or a chlorine atom is preferably a compound in which at least one of R ¹ and R ² is a perfluoroalkyl group or a chlorine atom, and the others are all fluorine atoms. Moreover, as a perfluoroalkyl group, a C1-C2 perfluoroalkyl group is preferable.
The repeating unit obtained by cyclopolymerization of the monomer (a) usually has a structure represented by the following formula (1a) or (1b).

  Examples of the monomer (a) that does not have a chlorine atom (hereinafter referred to as monomer (a-2)) include the following monomers. Methods for synthesizing these monomers are disclosed in JP-A-1-131215, JP-A-4-346957, and the like.

Perfluoro _{(3-oxa-1,5-hexadiene) (CF 2 = CF-CF} 2 -O-C
F = _CF 2), perfluoro _{(3-oxa-1,6-heptadiene) (CF 2 = CF-CF} 2 -CF 2 -O-CF = CF 2) ( hereinafter referred to as BVE), perfluoro (3-oxa -4 - _{methyl-1,6-heptadiene) (CF 2 = CF-CF} 2 -CF (CF 3) -O-CF = CF 2) ( hereinafter referred to as BVE-4M), perfluoro (3-oxa-4,4-dimethyl _{1,6-heptadiene) (CF 2 = CF-CF} 2 -C (CF 3) 2 -O-CF = CF 2), perfluoro (3-oxa-5-methyl-1,6-heptadiene) (CF _{2 = CF-CF (CF 3)} -CF 2 -O-CF = CF 2).

Examples of the monomer (a) having a chlorine atom (hereinafter referred to as monomer (a-1)) include the following monomers.
4-Chloro - perfluoro _{(3-oxa-1,5-hexadiene) (CF 2 = CF-CClF} -O-CF = CF 2), 4- chloro - perfluoro (3-oxa-1,6-heptadiene) (CF _{2 = CF-CF 2 -CClF-} O-CF = CF 2) ( hereinafter referred to as BVE-4CL), 4,4- dichloro - perfluoro _{(3-oxa-1,6-heptadiene) (CF 2 = CF-CF} 2 -CCl that _{2 -O-CF = CF 2)} ( hereinafter BVE-4DCL), 5- chloro - perfluoro _{(3-oxa-1,6-heptadiene) (CF 2 = CF-CClF} -CF 2 -O-CF = CF _2).

  The cyclized polymer may be a copolymer of two or more kinds of the monomer (a), or may be a copolymer of the monomer (a) and another copolymerizable monomer. . That is, the cyclized polymer may contain a repeating unit obtained by polymerizing another copolymerizable monomer in addition to the repeating unit obtained by cyclopolymerizing the monomer (a). As other copolymerizable monomers, monoenes are preferable, and these monoenes substantially have no hydrogen atom, and in the case of having a chlorine atom, chlorine directly bonded to the carbon atom constituting the polymerizable double bond. A compound having no atoms.

Specifically, for example, monomer (c) which is a monomer represented by the following formula (2), monomer (b) which is a monomer represented by the following formula (4), tetrafluoro perfluoroolefins, such as ethylene (hereinafter referred to as TFE), perfluoro _{(3-oxa-1-hexene) (CF 3 -CF 2 -CF 2} -O-CF = CF 2) , such as perfluoro (alkyl vinyl ether), perfluoro ( And perfluoro (methylenedioxolane) s such as 2-methylene-4-methyl-1,3-dioxolane (the following formula (6), hereinafter referred to as MMD).

  Except for the copolymer with the monomer (b), the ratio of the repeating unit in which the monomer (a) is cyclopolymerized with respect to all the repeating units in the cyclized polymer is suitably 20 to 100 mol%, 40-100 mol% is preferable, and 50-100 mol% is especially preferable. When this ratio is too small, it is difficult to obtain a polymer having good optical properties and mechanical properties. In the case of a copolymer with the monomer (b), the ratio of the repeating unit in which the monomer (a) is cyclopolymerized is not particularly limited.

  A monomer represented by the following formula (2) (hereinafter referred to as monomer (c)) is a preferred monomer for producing a cyclized polymer having a chlorine atom in the side chain. Since this monomer has two chlorine atoms at a position far from the polymerizable double bond, the cyclized polymer obtained by copolymerizing the monomer (c) and the monomer (a) is A cyclized polymer having a high refractive index and good physical properties is obtained.

However, n is an integer of 0 to ⁵ , and R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represent a C 1-9 perfluoroalkyl group, a chlorine atom or a fluorine atom. When n is 2 or more, a plurality of R ⁷ (same for R ⁸ ) may be different from each other. n is preferably an integer of 0 to 3, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are all preferably fluorine atoms. Moreover, when it has a perfluoroalkyl group, it is preferable that only one or both of R ⁵ and R ⁶ are perfluoroalkyl groups and the others are all fluorine atoms. Moreover, as a perfluoroalkyl group, a C1-C2 perfluoroalkyl group is preferable.

Specific examples of the monomer (c) include, for example, 6,7-dichloro-perfluoro (3-oxa-1-heptene) (CClF ₂ —CClF—CF ₂ —CF ₂ —O—CF═CF ₂ ) ( (Hereinafter referred to as 2CLBVE). A method for synthesizing the monomer (c) is disclosed in JP-A-1-131215.
The dioxole-based polymer is one or more polymers of fluorine-containing dioxoles or a copolymer of fluorine-containing dioxoles and other copolymerizable monomers. As the fluorine-containing dioxole, a monomer represented by the following formula (3) (hereinafter referred to as monomer (b)) is preferable.

However, R < ¹¹ > and R < ¹² > represent a C1-C9 perfluoroalkyl group or a fluorine atom each independently. At least one of R ¹¹ and R ¹² is preferably a perfluoroalkyl group. Moreover, as for carbon number of a perfluoroalkyl group, 1-6 are more preferable.

The dioxole-based polymer may be one or more polymers of the monomer (b), but is usually preferably a copolymer with another copolymerizable monomer. That is, it is preferable that the dioxole polymer contains a repeating unit obtained by polymerizing another copolymerizable monomer in addition to the repeating unit obtained by polymerizing the monomer (b). Other copolymerizable monomers are preferably monoenes and cycloene-polymerizable dienes, and these are monomers that substantially do not have hydrogen atoms, and preferably do not have chlorine atoms. Specifically, for example, the monomer (a), perfluoroolefins such as TFE, perfluoro (3-oxa-1-hexene) (CF ₃ -CF ₂ -CF ₂ -O)
-CF = CF ₂₎ perfluoro (alkyl vinyl ether) such as, a perfluoro (methylene dioxolane), and the like of the MMD like. As the other monomer, TFE is particularly preferable.

  Except for the copolymer with the monomer (a), the proportion of the repeating unit obtained by polymerizing the monomer (b) with respect to all the repeating units in the dioxole polymer is suitably 20 to 95 mol%, 30 to 90 mol% is preferable, and 35-85 mol% is especially preferable. If this ratio is too small or too large, it is difficult to obtain a polymer having good optical properties and mechanical properties.

  In the case of the copolymer of the monomer (a) and the monomer (b), the obtained fluoropolymer is used as a constituent of the amorphous fluororesin (A) or the amorphous fluororesin (B). The copolymerization ratio is selected depending on whether it is used as a constituent of (i.e., whether it is used for a high refractive index fluoropolymer or a low refractive index fluoropolymer). In the case of a high refractive index fluorine-containing polymer, the monomer (a) is a polymer having a high ratio of repeating units obtained by cyclopolymerization, and in the case of a low refractive index fluorine-containing polymer, the monomer (b) is polymerized. The polymer having a high ratio of the repeated units. In the former case, the proportion of the repeating unit in which the monomer (b) is polymerized is preferably more than 0 mol% to 40 mol%, particularly preferably 1 to 30 mol%. In the latter case, the proportion of the repeating unit in which the monomer (b) is polymerized is preferably 30 mol% to less than 100 mol%, particularly preferably 40 to 95 mol%.

  Among the dioxole polymers, a fluoropolymer having a repeating unit obtained by polymerizing a monomer represented by the following formula (4) (hereinafter referred to as monomer (b-1)) has a lower refractive index. That is, comparing the polymer having a repeating unit polymerized with PDD with the same polymer except that the repeating unit polymerized with monomer (b-1) is used instead of the repeating unit polymerizing PDD, the latter is more Has a low refractive index.

However, R ¹³ is a perfluoroalkyl group having 2 to 9 carbon atoms, R ¹⁴ represents a perfluoroalkyl group or a fluorine atom or less carbon 9 carbon atoms. R ¹³ is preferably a C 2-6 perfluoroalkyl group, and R ¹⁴ is preferably a C 1-6 perfluoroalkyl group or a fluorine atom.

Specific examples of the monomer (b-1) include the following.
Perfluoro (2-ethyl-1,3-dioxole) (wherein k is 1 in the following formula (7)),
Perfluoro (2-propyl-1,3-dioxole) (wherein k is 2 in the following formula (7)),
Perfluoro (2-pentyl-1,3-dioxole) (in the following formula (7), k is 4),
Perfluoro (2-ethyl-2-methyl-1,3-dioxole) (wherein j is 1 in the following formula (8)),
Perfluoro (2-methyl-2-propyl-1,3-dioxole) (wherein j is 2 in the following formula (8)),
Perfluoro (2-methyl-2-pentyl-1,3-dioxole) (wherein j is 4 in the following formula (8)).

Examples of the monomer (b) other than the monomer (b-1) include PDD and perfluoro (2-methyl-1,3-dioxole).
Among the monomers (b), a method for synthesizing PDD is disclosed in US Pat. No. 3,865,845. Further, the synthesis method of the copolymer is disclosed in US Pat. No. 3,978,030. The synthesis method of the other monomer (b) is disclosed in JP-A-2-117672, JP-A-5-194655 and the like.

  The core amorphous fluororesin (A) preferably contains a high refractive index agent. The high refractive index agent needs to have a higher refractive index than the fluoropolymer constituting the amorphous fluororesin (A) and have a high affinity for the fluoropolymer. Having high affinity means that it is sufficiently dissolved in the fluorine-containing polymer so that there is no insoluble matter and there is no possibility of forming a micro phase separation structure. If such an insoluble matter or a microphase separation structure exists, the portion causes light scattering. Therefore, as the high refractive index agent, a compound that is blended in the core fluoropolymer or less in the amount of its saturated solubility and that can sufficiently increase the refractive index of the core amorphous fluororesin (A) is used. .

  In order to have high affinity, the high refractive index agent is preferably a fluorine compound having a relatively low molecular weight. Moreover, since it is a high refractive index, it is preferable to have a chlorine atom, an aromatic nucleus, a metal component, etc. Particularly preferred are compounds having a chlorine atom and / or an aromatic nucleus. Further, the high refractive index agent is preferably a compound which does not substantially have a hydrogen atom, like the fluorine-containing polymer. Thereby, the transmission loss reduction in the near infrared region of the amorphous fluororesin containing the high refractive index agent is maintained. For these reasons, the high refractive index agent is preferably a fluorine compound having a relatively low molecular weight which has substantially no hydrogen atom and has a chlorine atom and / or an aromatic nucleus.

  The molecular weight of the high refractive index agent is preferably 2000 or less, and the average molecular weight of a polymer such as an oligomer is preferably 2000 or less. For example, fluorine compounds having a chlorine atom, fluorine-containing aromatic compounds, fluorine-containing condensed polycyclic compounds, metal chelate compounds and the like can be mentioned. Preferred high refractive index agents are a fluorine compound having substantially no hydrogen atom and having a chlorine atom, and a fluorine-containing aromatic compound having substantially no hydrogen atom. More preferred are fluorine-containing aromatic compounds having substantially no hydrogen atom, and among them, perfluoroaromatic compounds having 3 to 5 benzene nuclei in one molecule are particularly preferred. These high refractive index agents can be used alone or in admixture of two or more.

Examples of the fluorine-containing condensed polycyclic compound include perfluoroanthracene, perfluorofluorene, perfluorophenalene, perfluorophenanthrene and the like.
Examples of the metal chelate compound include perfluoro (tetraphenyltin).

  Examples of the fluorine compound having a chlorine atom include chloropentafluorobenzene, chloro-perfluoronaphthalene, and chlorotrifluoroethylene oligomer having an average molecular weight of 2000 or less. As the chlorotrifluoroethylene oligomer, commercially available one having an average molecular weight of 2000 or less can be used, and it can also be obtained by collecting fractions having an average molecular weight of 2000 or less by distillation.

  Fluorine-containing aromatic compounds include perfluoro (triphenylphosphine), perfluorobenzophenone, perfluorobiphenyl, perfluoroterphenyl, perfluoro (diphenyl sulfide), perfluoro (2,4,6-triphenyl-1,3,5-triazine) And perfluoro (1,3,5-triphenylbenzene) (hereinafter referred to as TPB). Of these, perfluoro (2,4,6-triphenyl-1,3,5-triazine) or TPB is preferable, and TPB is particularly preferable because of its high affinity with a fluoropolymer.

  In the amorphous fluororesin (A) containing a high refractive index agent, the ratio of the high refractive index agent in the amorphous fluororesin (A) is such that the amorphous fluororesin (A) has a desired refraction. The amount is not particularly limited as long as it is not less than the amount reaching the refractive index and not more than the solubility of the high refractive index agent in the fluoropolymer. Usually, the amorphous fluorine-containing resin (A) can be contained in an amount of 30% by mass or less. The content is preferably 1 to 20% by mass, and particularly preferably contains 5 to 20% by mass of a high refractive index agent.

  The clad amorphous fluororesin (B) preferably contains a fluorine-containing plasticizer having substantially no hydrogen atoms. The fluorine-containing plasticizer softens the clad amorphous fluororesin to improve the processability of the SI optical fiber, and gives a feature such that cracks are less likely to occur in a large diameter fiber. In addition, the addition of a fluorine-containing plasticizer having a high fluorine content also has the effect of further reducing the refractive index of the clad amorphous fluororesin.

  As the fluorine-containing plasticizer, perfluoropolyethers and the like are preferable. Examples of perfluoropolyethers include perfluoro (polyoxyalkylene alkyl ether). Specific examples of perfluoropolyethers include Krytox (trade name, manufactured by DuPont), Demnam (trade name, manufactured by Daikin Industries), Fomblin (trade name, manufactured by Augmont). From the viewpoint of being less volatile at the time of molding or use, the average molecular weight is preferably 1000 or more. The upper limit of the molecular weight is not particularly limited, but is preferably 20000 or less from the viewpoint of compatibility with the fluoropolymer of the clad.

  In the amorphous fluorine-containing resin (B) containing the fluorine-containing plasticizer, the ratio of the fluorine-containing plasticizer in the amorphous fluorine-containing resin (B) is such that the amorphous fluorine-containing resin (B) has a desired plasticizing effect. Is not particularly limited as long as the amount is such that the solubility of the fluorine-containing plasticizer in the fluorine-containing polymer is not more than the amount. Usually, the amorphous fluorine-containing resin (B) can be contained in an amount of 50% by mass or less. The content is preferably 1 to 40% by mass, and particularly preferably 5 to 40% by mass.

  The amorphous fluororesin (A) is preferably composed of a cyclized polymer as described above. The refractive index of the cyclized polymer itself constituting the amorphous fluororesin (A) is preferably 1.330 or more, particularly preferably 1.335 or more. The upper limit of the refractive index of the cyclized polymer itself is not particularly limited, but is usually 1.45.

  When the refractive index of the cyclized polymer itself is sufficiently high, the amorphous fluororesin (A) can be constituted only by the cyclized polymer without including a high refractive index agent. When the refractive index of the cyclized polymer itself is not sufficiently high or when the refractive index of the amorphous fluororesin (B) is relatively high and the refractive index difference from the cyclized polymer is not large, a high refractive index agent It is preferable to use an amorphous fluororesin (A) containing The refractive index of the amorphous fluororesin (A) which may contain a high refractive index agent is preferably 1.340 or more, more preferably 1.345 or more, further preferably 1.350 or more, most preferably 1.355 or more. preferable. The upper limit of the refractive index of the amorphous fluororesin (A) is not particularly limited, but is usually 1.5.

  In the present invention, the amorphous fluororesin (A-1) composed of a fluoropolymer having substantially no hydrogen atom and having a chlorine atom in the side chain is the above-mentioned amorphous fluororesin (A). Of these, it is composed of a fluoropolymer having a chlorine atom in the side chain. Since the amorphous fluororesin (A) is preferably a cyclized polymer, the amorphous fluororesin (A-1) is also preferably a cyclized polymer. The refractive index of the fluoropolymer itself having a chlorine atom in the side chain is preferably 1.345 or more, particularly preferably 1.350 or more. Similarly, the refractive index of the amorphous fluororesin (A-1) is preferably 1.345 or more, particularly preferably 1.350 or more.

  The fluoropolymer having a chlorine atom in the side chain constituting the amorphous fluororesin (A-1) is a polymer containing a repeating unit obtained by cyclopolymerization of the monomer (a-1) (the following single unit). The monomer (a-2) may have a cyclic polymerized repeating unit), and has no chlorine atom directly bonded to the carbon atom constituting the polymerizable double bond and other carbon atoms A polymer containing a repeating unit obtained by polymerizing a copolymerizable monomer having a chlorine atom (particularly, a monoene containing such a chlorine atom) and a repeating unit obtained by cyclopolymerizing the monomer (a), preferable. As the chlorine atom-containing copolymerizable monomer, the monomer (c) is particularly preferable. In addition, the monomer which does not have a chlorine atom among monomers (a) is called monomer (a-2) below.

  A particularly preferred fluoropolymer having a chlorine atom in the side chain is a polymer having a repeating unit obtained by cyclopolymerization of the monomer (a-1) (provided that the monomer (a-2) is cyclopolymerized. A polymer having no repeating unit), a polymer having a repeating unit in which the monomer (a-1) is cyclopolymerized and a repeating unit in which the monomer (a-2) is cyclopolymerized, and a single amount It is a polymer having a repeating unit in which the body (a) is cyclopolymerized and a repeating unit in which the monomer (c) is polymerized.

  Since the amorphous fluororesin (A-1) is composed of a fluorine-containing polymer having a chlorine atom, it has a sufficiently high refractive index even without including a high refractive index agent. However, in some cases, a high refractive index agent may be included. The amorphous fluororesin (A) includes the amorphous fluororesin (A-1) as its category, but in particular when it is composed of a fluoropolymer having no chlorine atom, a high refractive index agent is used. It is preferable to include. Even when the amorphous fluororesin (A) is composed of a fluoropolymer having no chlorine atom, the difference in refractive index from the amorphous fluororesin (B) combined as a clad is large. Need not contain a high refractive index agent.

  The amorphous fluororesin (B) is preferably composed of a dioxole polymer as described above. The refractive index of the dioxole polymer is not particularly limited as long as the refractive index difference between the dioxole polymer constituting the amorphous fluororesin (B) and the amorphous fluororesin (A) is large. The refractive index of the dioxol polymer itself constituting the fluororesin (B) is preferably less than 1.330, particularly preferably less than 1.310. In order to achieve a higher refractive index difference with the amorphous fluororesin (A), the refractive index of the dioxole polymer itself is more preferably less than 1.300, and particularly preferably less than 1.296. The lower limit of the refractive index of the dioxole polymer itself is not particularly limited, but is usually 1.290. Although not limited to a dioxole polymer, an amorphous fluororesin composed of a fluoropolymer having a refractive index of less than 1.300 is hereinafter referred to as an amorphous fluororesin (B-2).

  The fluorine-containing polymer having a repeating unit obtained by polymerizing the monomer (b-1) as described above is a fluorine-containing polymer having a repeating unit obtained by polymerizing the monomer (b) other than the monomer (b-1). Lower refractive index than coalescence. The amorphous fluororesin (B) composed of a fluoropolymer having a repeating unit obtained by polymerizing the monomer (b-1) is hereinafter referred to as amorphous fluororesin (B-3). Further, among the fluorinated polymers having a repeating unit obtained by polymerizing the monomer (b-1), a more preferred polymer is a fluorinated polymer having a refractive index of less than 1.300, particularly less than 1.296.

  Therefore, the fluoropolymer constituting the amorphous fluororesin (B-2) and the amorphous fluororesin (B-3) has a repeating unit in which the monomer (b-1) is polymerized and A fluoropolymer having a refractive index of less than 1.300 is preferred. This particularly preferable fluoropolymer is a copolymer having a copolymerization molar ratio of the monomer (b-1) and TFE in the range of 99 to 20/1 to 80.

  The refractive index of the amorphous fluororesin (B) which may contain a fluorine-containing plasticizer is preferably less than 1.330, particularly preferably less than 1.310. Particularly preferred amorphous fluororesin (B) has a refractive index of less than 1.300, most preferably less than 1.296. The lower limit of the refractive index of the amorphous fluororesin (B) is not particularly limited, but is usually 1.285.

  The SI type optical fiber of the present invention can be manufactured by a known method for manufacturing an SI type optical fiber. For example, it can be produced by the method described in Japanese Patent No. 2821935. In addition, the SI type optical fiber of the present invention can be manufactured by applying the refractive index distribution type plastic optical fiber manufacturing method described in JP-A-8-5848 and JP-A-11-167030. . For example, an SI type optical fiber is manufactured in accordance with a method of manufacturing a preform for SI type optical fiber production (hereinafter simply referred to as a preform) and spinning from the preform to form an SI type optical fiber, or a method of performing multicolor spinning with an extruder. And the like.

  The SI type optical fiber of the present invention has no increase in transmission loss due to water absorption due to the water / oil repellency effect of fluorine atoms, and has high solvent resistance. Further, the optical fiber has a small transmission loss over a wide wavelength range from the visible region to the near infrared region.

  Further, the SI type optical fiber of the present invention can have a numerical aperture (NA) of 0.415 or more because the difference in refractive index between the core and the clad can be sufficiently increased. The SI type optical fiber having a large numerical aperture can receive light from a wide angle, that is, can detect a signal from a wide angle as a sensor, can increase the coupling efficiency between the light source and the fiber, that is, has high efficiency and energy of the light source. Can be input / transmitted, and bending loss during transmission can be minimized.

The SI type optical fiber of the present invention can be used in the form of an optical fiber cord, an optical fiber cable, or a bundled optical fiber cable by being further coated.
The SI optical fiber of the present invention has a wavelength of 600 to 1600 nm and a transmission loss of 100 m can be 5 db or less (that is, 50 dB / km or less). Such a low level transmission loss is very advantageous in a wide wavelength region of wavelengths of 600 to 1600 nm. That is, by using the same wavelength as the quartz optical fiber, it is easy to connect to the quartz optical fiber, and it is less expensive than a conventional plastic optical fiber that has to use a wavelength shorter than 600 to 1600 nm. There are benefits.

On the other hand, plastic optical fibers have a large fiber diameter, and are easily connected to a light source / light receiving element or to each other. Since the SI type optical fiber of the present invention has drastically improved heat resistance, it has high thermal stability and can prevent a reduction in transmission loss even when exposed to a high temperature of room temperature or higher for a long time.

(Example)
EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these. Part represents part by mass. Examples 1 to 3 are monomer synthesis examples in which fluorine-containing dioxoles were synthesized. Examples 4 to 27 are polymer production examples for producing a fluoropolymer constituting an amorphous fluororesin. Examples 28 to 41 are examples of producing an amorphous fluororesin for producing an SI type optical fiber. Examples 42 to 58 are examples of making SI type optical fibers.

[Monomer synthesis example]
Example 1 Synthesis of perfluoro (2-methyl-2-propyl-1,3-dioxole) (hereinafter referred to as PMPROD).
Into a ₂ L glass four-necked flask, 1.5 kg of 60% fuming sulfuric acid was added, and 446 g of CF ₃ (CF ₂ ) ₅ I was added dropwise using a dropping funnel. Stirring was continued for 24 hours while maintaining the temperature at 65 ° C. After the reaction, the reaction mixture was cooled and separated into two phases. Only the upper layer was collected and distilled to obtain 190 g (yield 60%) of colorless and transparent CF ₃ (CF ₂ ) ₄ COF.

Next, 1 L of ethanol and a few drops of phenolphthalein were placed in a ₂ L polypropylene beaker, and 190 g of CF ₃ (CF ₂ ) ₄ COF was added dropwise while stirring with a magnetic stirrer. To the solution was added dropwise an ethanol solution of 10% sodium hydroxide until the solution became neutral. Ethanol was removed from the obtained reaction solution using an evaporator, and the obtained solid was transferred to a vacuum dryer and vacuum-dried at 100 ° C. for 18 hours. Next, the solid after vacuum drying was transferred to a 5 L glass flask, and the flask was heated for 24 hours while maintaining 250 to 270 ° C. in an oil bath under reduced pressure using a vacuum pump through a dry ice strap. The liquid collected in the dry eye strap was distilled to obtain 113 g (yield 75%) of CF ₃ CF ₂ CF ₂ CF═CF ₂ .

Next, 1000 g of a 15% aqueous sodium hypochlorite solution and 8 g of trioctylmethylammonium chloride were placed in a 2 L glass four-necked flask and cooled until the internal temperature reached 10 to 15 ° C. with good stirring. Thereto, 113 g of CF ₃ CF ₂ CF ₂ CF═CF ₂ was added dropwise so as to keep the internal temperature at 20 to 30 ° C. Then, with monitoring the reaction by gas _{chromatograph, CF 3 CF 2 CF 2 CF} = CF 2 as a raw material is reacted until nearly gone. The lower layer product was extracted by two-phase separation, and washed with ion-exchanged water three times to remove residual sodium hypochlorite. Further, the crude product was distilled to obtain 83 g (yield 70%) of pure fluorine-containing epoxide (perfluoro (1,2-epoxypentane)).

Next, 3 g of aluminum chloride was put into a 200 mL glass four-necked flask and activated by adding 10 g of trichlorofluoromethane. Thereto was added dropwise 83 g of the fluorine-containing epoxide synthesized above so as to keep the internal temperature at 20 to 30 ° C. with good stirring. Then, it was made to react until the raw material was almost consumed at reaction temperature 20-40 degreeC, tracking reaction by a gas chromatograph. Subsequently, the crude product was isolated by filtration and distilled to obtain 76 g (yield 92%) of pure CF ₃ CF ₂ CF ₂ COCF ₃ .

Next, 25 g of 2-chloroethanol was placed in a 300 mL glass four-necked flask, and 76 g of CF ₃ CF ₂ CF ₂ COCF ₃ was added dropwise at room temperature while stirring. The obtained reaction crude liquid was dropped into 500 g of 20% aqueous sodium hydroxide solution in another 1 L glass flask while vigorously stirring. This reaction solution was washed with water three times and distilled to obtain 77 g (yield) of the desired dioxolane compound (4,4,5,5-tetrahydro-perfluoro (2-methyl-2-propyl-1,3-dioxolane)). Rate 87%).

  Next, 77 g of the dioxolane compound was placed in a 500 mL glass four-necked flask equipped with a stirrer, a dry ice reflux condenser, a chlorine gas blowing tube, and a thermocouple thermometer, and introduction of chlorine gas was started at 5 ° C. Since the reaction was intense at the beginning of the reaction, chlorine was introduced slowly. The temperature was gradually raised, and the reaction was continued at 78 ° C. at the end, and the reaction was terminated when no chlorine was consumed. 100 g (yield 89%) of the obtained tetrachlorodioxolane compound (4,4,5,5-tetrachloro-perfluoro (2-methyl-2-propyl-1,3-dioxolane)) was used without purification. Used in the next reaction.

  Next, in a 500 mL glass three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer, 50 g of antimony trifluoride, 5 g of antimony pentachloride, and perfluoro (2-butyltetrahydrofuran) (hereinafter referred to as PBTHF) as a solvent. 50 mL was added, 100 g of the tetrachlorodioxolane compound was added at room temperature, and reflux was continued for 24 hours. Under these conditions, only a compound in which two chlorines at the target vicinal position were substituted with fluorine was selectively obtained. After cooling to room temperature, only the supernatant liquid is collected by decantation and subjected to distillation under reduced pressure, whereby the desired dichlorodioxolane compound (4,5-dichloro-perfluoro (2-methyl-2-propyl-1,3- 78 g (yield 85%) of dioxolane)) were obtained.

  Next, 15 g of magnesium powder, 1 g of iodine, 0.5 g of mercuric chloride and 350 mL of tetrahydrofuran are placed in a 1 L glass four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermocouple thermometer. Used and heated. When refluxing started, the heating was stopped and 78 g of the above dichlorodioxolane compound was slowly added dropwise. The reactor was cooled as necessary because of intense heat generation. After completion of the dropwise addition, the reaction vessel was evacuated and tetrahydrofuran and the product were collected with a liquid nitrogen trap. The collected product was poured into cold water, the lower fluorocarbon phase was separated, and 25 g (yield: 40%) of the target PMPROD (with j of 2 in the formula (8)) having a purity of 99.5% by distillation under reduced pressure. )Obtained. This was used for the following polymerization.

Example 2 Synthesis of perfluoro (2-methyl-2-pentyl-1,3-dioxole) (hereinafter referred to as PMPEND).
Into a ₂ L glass four-necked flask, 1.5 kg of 60% fuming sulfuric acid was added, and 546 g of CF ₃ (CF ₂ ) ₇ I was added dropwise using a dropping funnel. Stirring was continued for 20 hours while maintaining the temperature at 65 ° C. After the reaction, the reaction mixture was cooled and separated into two phases. Only the upper layer was collected and distilled to obtain 270 g of colorless and transparent CF ₃ (CF ₂ ) ₆ COF (yield 65%).

Next, several drops of 1 L of ethanol and phenolphthalein were placed in a ₂ L polypropylene beaker, and 270 g of CF ₃ (CF ₂ ) ₆ COF was added dropwise while stirring with a magnetic stirrer. To the solution was added dropwise an ethanol solution of 10% sodium hydroxide until the solution became neutral. Ethanol was removed from the obtained reaction solution using an evaporator, and the resulting solid was transferred to a vacuum dryer and vacuum dried at 100 ° C. for 15 hours. Next, the solid after vacuum drying was transferred to a 5 L glass flask, and the flask was heated for 24 hours while maintaining a temperature of 260 to 280 ° C. in an oil bath under a reduced pressure using a vacuum pump through a dry ice strap. The liquid collected in the dry eye strap was distilled to obtain 180 g (yield 79%) of CF ₃ (CF ₂ ) ₄ CF═CF ₂ .

Next, 1000 g of a 15% sodium hypochlorite aqueous solution and 10 g of trioctylmethylammonium chloride were placed in a 2 L glass four-necked flask and cooled until the internal temperature became 10 to 15 ° C. with good stirring. Thereto, 180 g of CF ₃ (CF ₂ ) ₄ CF═CF ₂ was added dropwise so as to keep the internal temperature at 20 to 30 ° C. Subsequently, the mixture was allowed to react until _{CF 3 (CF 2) 4 CF} = CF 2 as a raw material with monitoring the reaction by gas chromatograph is substantially consumed. The lower layer product was extracted by two-phase separation, and washed with ion-exchanged water three times to remove residual sodium hypochlorite. Further, the crude product was distilled to obtain 122 g (yield 65%) of pure fluorine-containing epoxide (perfluoro (1,2-epoxyheptane)).

Next, 3 g of aluminum chloride was put into a 200 mL glass four-necked flask and activated by adding 10 g of trichlorofluoromethane. 120 g of the fluorine-containing epoxide synthesized above was added dropwise thereto so as to keep the internal temperature at 20 to 30 ° C. with good stirring. Then, it was made to react until the raw material was almost consumed at reaction temperature 20-40 degreeC, tracking reaction by a gas chromatograph. Subsequently, the crude product was isolated by filtration and distilled to obtain 108 g (yield 90%) of pure CF ₃ (CF ₂ ) ₄ COCF ₃ .

Next, 23 g of 2-chloroethanol was placed in a 300 mL glass four-necked flask, and 108 g of CF ₃ (CF ₂ ) ₄ COCF ₃ was added dropwise at room temperature while stirring. The obtained reaction crude liquid was dropped into 500 g of 20% aqueous sodium hydroxide solution in another 1 L glass flask while vigorously stirring. The reaction solution was washed with water three times using a separatory funnel and distilled to give the desired dioxolane compound (4,4,5,5-tetrahydro-perfluoro (2-methyl-2-pentyl-1,3-dioxolane). )) (103 g, yield 85%).

  Next, 103 g of the dioxolane compound was placed in a 500 mL glass four-necked flask equipped with a stirrer, a dry ice reflux condenser, a chlorine gas blowing tube, and a thermocouple thermometer, and introduction of chlorine gas was started at 5 ° C. Since the reaction was intense at the beginning of the reaction, chlorine was introduced slowly. The temperature was gradually raised and the reaction was continued at 80 ° C. at the end, and the reaction was terminated when no more chlorine was consumed. 121 g (yield 88%) of the obtained tetrachlorodioxolane compound (4,4,5,5-tetrachloro-perfluoro (2-methyl-2-pentyl-1,3-dioxolane)) was directly purified without purification. Used in the next reaction.

  Next, in a 500 mL glass three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer, 50 g of antimony trifluoride, 5 g of antimony pentachloride, and 50 mL of PBTHF are used as a solvent. And continued to reflux for 32 hours. Under these conditions, only a compound in which two chlorines at the target vicinal position were substituted with fluorine was selectively obtained. After cooling to room temperature, only the supernatant liquid is collected by decantation and subjected to distillation under reduced pressure, whereby the desired dichlorodioxolane compound (4,5-dichloro-perfluoro (2-methyl-2-pentyl-1,3- 99 g (yield 87%) of dioxolane)).

  Next, 13 g of magnesium powder, 2 g of iodine, 0.5 g of mercuric chloride, and 350 mL of tetrahydrofuran are placed in a 1 L glass four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermocouple thermometer. Used and heated. When refluxing started, the heating was stopped and 99 g of the above dichlorodioxolane compound was slowly added dropwise. The reactor was cooled as necessary because of intense heat generation. After completion of the dropwise addition, the reaction vessel was evacuated and tetrahydrofuran and the product were collected with a liquid nitrogen trap. The collected material was poured into cold water, the lower fluorocarbon phase was separated, and 34 g (yield 41%) of the target PMPEND (with j = 4 in the above formula (8)) having a purity of 99.2% by distillation under reduced pressure. ) This was used for the following polymerization.

Example 3 Synthesis of perfluoro (2-pentyl-1,3-dioxole) (hereinafter referred to as PPD).
Into a ₂ L glass four-necked flask, 1.5 kg of 60% fuming sulfuric acid was added, and 446 g of CF ₃ (CF ₂ ) ₅ I was dropped using a dropping funnel. Stirring was continued for 18 hours while maintaining at 65 ° C. After the reaction, the reaction mixture was cooled and separated into two phases. Only the upper layer was collected and distilled to obtain 200 g (yield 63%) of colorless and transparent CF ₃ (CF ₂ ) ₄ COF.

Next, 51 g of 2-chloroethanol was put into a 1 L polypropylene beaker, 200 g of CF ₃ (CF ₂ ) ₄ COF was added dropwise, 50 g of pyridine was further added, washed with water, and distilled to give CF ₃ 190 g (yield 80%) of (CF ₂ ) ₄ COOCH ₂ CH ₂ Cl was obtained.

Next, 500 mL of dimethyl sulfoxide and 7.3 g of sodium hydride (dispersed in 60% mineral oil) were placed in a 1 L glass four-necked flask, and 190 g of CF ₃ (CF ₂ ) ₄ COOCH synthesized above was stirred while stirring. ₂ CH ₂ Cl was added to keep the temperature below 20 ° C. The stirring was continued overnight while maintaining the temperature at 30 ° C. or lower. Distillation under reduced pressure gave 86 g (yield 50%) of the desired dioxolane compound (2,4,4,5,5-pentahydro-perfluoro (2-pentyl-1,3-dioxolane)).

  Next, 86 g of the dioxolane compound was placed in a 500 mL glass four-necked flask equipped with a stirrer, a dry ice reflux condenser, a chlorine gas blowing tube, and a thermocouple thermometer, and introduction of chlorine gas was started at 2 ° C. Since the reaction was intense at the beginning of the reaction, chlorine was introduced slowly. The temperature was gradually raised, and the reaction was continued at 82 ° C. at the end, and the reaction was terminated when no chlorine was consumed. 95 g (yield 74%) of the obtained pentachlorodioxolane compound (2,4,4,5,5-pentachloro-perfluoro (2-pentyl-1,3-dioxolane)) was used in the next reaction without purification. Used for.

  Next, in a 500 mL glass three-necked flask equipped with a stirrer, a reflux condenser, and a thermocouple thermometer, 50 g of antimony trifluoride, 5 g of antimony pentachloride, and 50 mL of PBTHF are used as a solvent, and 95 g of the above pentachlorodioxolane compound at room temperature And continued to reflux for 24 hours. Under these conditions, only a compound in which the chlorine at the 2-position and the two chlorines at the vicinal position were substituted with fluorine were selectively obtained. After cooling to room temperature, only the supernatant liquid was collected by decantation and subjected to distillation under reduced pressure, whereby 73 g of the desired dichlorodioxolane compound (4,5-dichloro-perfluoro (2-pentyl-1,3-dioxolane)) (Yield 85%) was obtained.

  Next, 15 g of magnesium powder, 1 g of iodine, 0.5 g of mercuric chloride and 350 mL of tetrahydrofuran are placed in a 1 L glass four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermocouple thermometer. Used and heated. When refluxing started, the heating was stopped and 73 g of the dichlorodioxolane compound was slowly added dropwise. The reactor was cooled as necessary because of intense heat generation. After completion of the dropwise addition, the reaction vessel was evacuated and tetrahydrofuran and the product were collected with a liquid nitrogen trap. The collected product was poured into cold water, the lower fluorocarbon phase was separated, and 22 g (yield 35%) of the target PPD (the following formula (9)) having a purity of 99.7% was obtained by distillation under reduced pressure. This was used for the following polymerization.

¹⁹ F-NMR (CDCl ₃ , CFCl ₃ standard) δ ppm; -70.1 (1F), -80.9 (3F), -121.8 to -126.0 (9F), -157.9 (1F) .
[Polymer production example]
In the following examples 4 to 28, a glass transition temperature _{T g} of the fluorine-containing polymer or amorphous fluororesin was measured using differential scanning calorimetry (according to JIS-K7121). The refractive index was measured using an Abbe refractometer. The molecular weight was measured as the number average molecular weight _{Mn in} terms of polymethyl methacrylate by gel permeation chromatography (GPC) using a dichloropentafluoropropane solvent (hereinafter referred to as R225). Intrinsic viscosity [η] (unit dl / g) was measured at 30 ° C. after dissolving in PBTHF (however, R225 for the polymer P-4 obtained in Example 7).
In the following polymer production examples, the polymer fluorination treatment was performed by treating the polymer in an atmosphere of fluorine / nitrogen mixed gas (fluorine gas concentration 20% by volume) at 250 ° C. for 5 hours (conditions). If you change the) clearly.

(Example 4) Polymer P-1 (BVE polymer)
A 5 L glass flask was charged with 750 g of BVE, 4 kg of ion-exchanged water (hereinafter also referred to as water), 260 g of methanol, and 3.7 g of diisopropyl peroxydicarbonate. After replacing the system with nitrogen, suspension polymerization was carried out at 40 ° C. for 22 hours to obtain 690 g of a polymer having an _Mn of about 5 × 10 ⁴ . This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-1). Of the polymer P-1 [η] is 0.25, _{T g} is 108 ° C., the refractive index is 1.342, was a transparent glassy polymer tough at room temperature.

(Example 5) Polymer P-2 (BVE-4M polymer)
In a glass ampoule, 2 g of BVE-4M and 6.2 mg of diisopropyl peroxydicarbonate were put, frozen in liquid nitrogen, vacuum degassed and sealed. After heating in an oven at 40 ° C. for 20 hours, the solidified content was taken out and dried at 200 ° C. for 1 hour. The yield of the obtained polymer was 99%. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-2). [Η] of polymer P-2 was 0.44, M _n was 131500, the refractive index was 1.33, and T _g was 124 ° C. The tensile properties of the polymer P-2 were a tensile elastic modulus of 1430 MPa, a yield stress of 36 MPa, and a breaking elongation of 4.2%.

(Example 6) Polymer P-3 (BVE / BVE-4M copolymer)
In a 200 mL autoclave, 80 g of water, 15 g of BVE-4M, 15 g of BVE,
75 mg of perfluorobenzoyl peroxide and 2.4 g of methanol were added. After the autoclave was purged with nitrogen, the autoclave was heated until the internal temperature of the autoclave reached 70 ° C. and polymerized for 20 hours. The obtained polymer was washed with water and methanol and then dried at 200 ° C. for 1 hour. The yield of the obtained polymer was 85%. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-3). [Eta] of the polymer P-3 0.35, the refractive index 1.336, _{T g} was 116 ° C..

(Example 7) Polymer P-4 (BVE-4CL polymer)
In a glass ampoule, 5 g of BVE-4CL and 12.5 mg of diisopropylperoxydicarbonate were placed, frozen in liquid nitrogen, vacuum sealed and sealed. After heating in an oven at 40 ° C. for 20 hours, the solidified content was taken out and dried at 200 ° C. for 1 hour. The yield of the obtained polymer was 80%. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-4). [Η] of polymer P-4 was 0.20, M _n was 121500, refractive index was 1.372, and T _g was 126 ° C. The tensile properties of the polymer P-4 were a tensile elastic modulus of 1700 MPa, a yield stress of 50 MPa, and a yield elongation of 3.8%.

(Example 8) Polymer P-5 (BVE / BVE-4CL copolymer)
A 200 mL autoclave was charged with 80 g of water, 20 g of BVE-4CL, 15 g of BVE, 80 mg of perfluorobenzoyl peroxide, and 2.0 g of methanol. After the autoclave was purged with nitrogen, the autoclave was heated until the internal temperature of the autoclave reached 70 ° C. and polymerized for 24 hours. The obtained polymer was washed with water and methanol and then dried at 200 ° C. for 1 hour. The yield of the obtained polymer was 80%. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-5). Of the polymer P-5 [η] is 0.30, the refractive index 1.36, _{T g} was 120 ° C..

(Example 9) Polymer P-6 (BVE-4DCL polymer)
A 100 mL stainless steel autoclave was charged with 50 g of trichlorotrifluoroethane, 30 g of BVE-4DCL, and 0.1 g of diisopropyl peroxydicarbonate. The autoclave was heated and stirred at 50 ° C. for 3 days, and then the autoclave was opened and washed with methanol. The obtained polymer was taken out, and the solvent and the remaining monomer were distilled off under reduced pressure to obtain 29 g of a colorless and transparent polymer. The yield of the obtained polymer was 96%. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-6). M _n of polymer P-6 was 123,000, the refractive index was 1.41, and T _g was 168 ° C. The tensile properties of the polymer P-6 were a tensile elastic modulus of 1690 MPa, a yield stress of 50 MPa, and a yield elongation of 3.6%.

(Example 10) Polymer P-7 (BVE / BVE-4DCL copolymer)
A 200 mL autoclave was charged with 80 g of water, 22 g of BVE-4DCL, 15 g of BVE, 75 mg of perfluorobenzoyl peroxide, and 2.0 g of methanol. After the autoclave was purged with nitrogen, the autoclave was heated until the internal temperature of the autoclave reached 70 ° C. and polymerized for 28 hours. The obtained polymer was washed with water and methanol and then dried at 200 ° C. for 2 hours. The yield of the obtained polymer was 80%. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-7). [Eta] of the polymer P-7 0.28, the refractive index 1.38, _{T g} was 145 ° C..

(Example 11) Polymer P-8 (BVE / 2CLBVE copolymer)
A 200 mL autoclave was charged with 80 g of water, 12 g of 2CLBVE, 15 g of BVE, 75 mg of perfluorobenzoyl peroxide, and 1.0 g of methanol. After the autoclave was purged with nitrogen, the autoclave was heated until the internal temperature of the autoclave reached 75 ° C. and polymerized for 40 hours. The obtained polymer was washed with water and methanol and then dried at 200 ° C. for 2 hours. The yield of the obtained polymer was 70%. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-8). [Η] of polymer P-8 was 0.25, refractive index was 1.35, and _Tg was 98 ° C.

(Example 12) Polymer P-9 (PDD / TFE copolymer)
The PDD and TFE at a mass ratio of 80:20, and a radical polymerization using a PBTHF as a solvent, _{T g} is the _{M n} at 160 ° C. to obtain a polymer of about 1.7 × 10 ^5. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-9). The polymer P-9 was colorless and transparent, and the refractive index was 1.305.

(Example 13) Polymer P-10 (PMPROD / TFE copolymer)
In a weight ratio of 85:15 to PMPROD and TFE, and radical polymerization using a PBTHF as a solvent, _{T g} is the _{M n} at 200 ° C. to obtain a polymer of about 1.5 × 10 ^5. This polymer was subjected to a fluorination treatment (however, the treatment time was 7 hours) to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-10). The polymer P-10 was colorless and transparent, and the refractive index was 1.298.

(Example 14) Polymer P-11 (PMPEND / TFE copolymer)
In a weight ratio of 85:15 to PMPEND and TFE, and radical polymerization using a PBTHF as a solvent, _{T g} is the _{M n} at 190 ° C. to obtain a polymer of about 1.3 × 10 ^5. This polymer was subjected to a fluorination treatment (however, the treatment time was 6 hours) to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-11). The polymer P-11 was colorless and transparent, and the refractive index was 1.295.

(Example 15) Polymer P-12 (PDD / BVE-4M copolymer)
The PDD and BVE-4M in a mass ratio of 50:50, and a radical polymerization using a PBTHF as a solvent, _{T g} is at 170 ° C. [eta] is to obtain a polymer of 0.34. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-12). The polymer P-12 was colorless and transparent, and the refractive index was 1.320.

(Example 16) Polymer P-13 (PMPROD / BVE-4M copolymer)
The PBTHF the PMPROD and BVE-4M in a weight ratio of 45:55 to radical polymerization using a solvent, _{T g} is at 160 ° C. [eta] is to obtain a polymer of 0.32. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-13). The polymer P-13 was colorless and transparent, and the refractive index was 1.318.

(Example 17) Polymer P-14 (PMPEND / BVE-4M copolymer)
Radical polymerization using PMPEND and BVE-4M of PBTHF in a mass ratio of 50:50 as the solvent, [η] _{T g} is at 162 ° C. to obtain a polymer of 0.37. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-14). The polymer P-14 was colorless and transparent, and the refractive index was 1.319.

(Example 18) Polymer P-15 (PPD / BVE-4M copolymer)
The PBTHF the PPD and BVE-4M in a weight ratio of 55:45 to radical polymerization using a solvent, _{T g} is at 160 ° C. [eta] is to obtain a polymer of 0.33. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-15). The polymer P-15 was colorless and transparent, and the refractive index was 1.310.

(Example 19) Polymer P-16 (PDD / PHVE copolymer)
That PDD and perfluoro _{(3,6-dioxa-4-methyl-1-nonene) (CF 2 = CF-O} -CF (CF 3) -CF 2 -O-CF 2 -CF 2 -CF 3) ( hereinafter PHVE ) radical polymerization using PBTHF as a solvent in a weight ratio 85:15, _{T g} is at 182 ° C. [eta] is to obtain a polymer of 0.38. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-16). The polymer P-16 was colorless and transparent, and the refractive index was 1.300.

(Example 20) Polymer P-17 (PMPROD / BVE copolymer)
Radical polymerization using PMPROD and BVE a PBTHF in a mass ratio of 50:50 as the solvent, [η] _{T g} is at 145 ° C. to obtain a polymer of 0.30. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-17). The polymer P-17 was colorless and transparent, and the refractive index was 1.321.

(Example 21) Polymer P-18 (PMPEND / BVE copolymer)
Radical polymerization using PMPEND and BVE a PBTHF in a mass ratio of 50:50 as the solvent, _{T g} is at 0.99 ° C. is [eta] to obtain a polymer of 0.32. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and thermal stability (hereinafter referred to as polymer P-18). The polymer P-18 was colorless and transparent, and the refractive index was 1.320.

(Example 22) Polymer P-19 (PPD / BVE copolymer)
The PBTHF the PPD and BVE at a weight ratio of 50:50 to radical polymerization using a solvent, _{T g} is at 148 ° C. [eta] is to obtain a polymer of 0.35. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-19). The polymer P-19 was colorless and transparent, and the refractive index was 1.322.

(Example 23) Polymer P-20 (PDD / MMD copolymer)
The PBTHF the PDD and MMD in a mass ratio of 65:35 to radical polymerization using a solvent, _{T g} is at 170 ° C. [eta] is to obtain a polymer of 0.30. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-20). The polymer P-20 was colorless and transparent, and the refractive index was 1.325.

(Example 24) Polymer P-21 (PMPROD / MMD copolymer)
Radical polymerization using PMPROD and MMD a PBTHF in a mass ratio of 65:35 as the solvent, [η] _{T g} is at 168 ° C. to obtain a polymer of 0.31. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and heat stability (hereinafter referred to as polymer P-21). The polymer P-21 was colorless and transparent, and the refractive index was 1.324.

(Example 25) Polymer P-22 (PMPEND / MMD copolymer)
Radical polymerization using PMPEND and MMD a PBTHF in a mass ratio of 60:40 as the solvent, [η] _{T g} is at 142 ° C. to obtain a polymer of 0.38. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-22). The polymer P-22 was colorless and transparent, and the refractive index was 1.327.

Example 26: Polymer P-23 (PPD / MMD copolymer)
Radical polymerization using PBTHF the PPD and MMD in a mass ratio of 65:35 as the solvent, [η] _{T g} is at 162 ° C. to obtain a polymer of 0.29. This polymer was subjected to a fluorination treatment to obtain a polymer having good light transmittance and heat stability (hereinafter referred to as polymer P-23). The polymer P-23 was colorless and transparent, and the refractive index was 1.325.

(Example 27) Polymer P-24 (PPD / TFE copolymer)
Radical polymerization using PBTHF the PPD and TFE in a mass ratio of 85:15 as the solvent, [η] _{T g} is at 162 ° C. to obtain a polymer of 0.35. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-24). The polymer P-24 was colorless and transparent, and the refractive index was 1.307.

(Example 28) Polymer P-25 (PPD polymer)
In a glass ampoule, 5 g of PPD, 6.0 mg of sulfuryl chloride, and 5.0 mg of diisopropyl peroxydicarbonate were placed, frozen in liquid nitrogen, vacuum degassed and sealed. After heating in an oven at 40 ° C. for 3 hours, the solidified content was taken out and dried at 200 ° C. for 1 hour. The yield of the obtained polymer was 97%. This polymer was fluorinated to obtain a polymer having good light transmission and thermal stability (hereinafter referred to as polymer P-25). [Η] of polymer P-4 was 0.87, M _n was 105000, refractive index was 1.320, and T _g was 105 ° C. The tensile properties of the polymer P-4 were a tensile elastic modulus of 500 MPa and a breaking elongation of 63%.

[Production example of amorphous fluororesin]
(Examples 29 to 43) Resin R-1 to Resin R-15
Polymers P-1 and TPB were mixed (containing 7.4% by mass of the latter with respect to the total of both), and melted and mixed at 250 ° C. to produce a uniform mixture. Hereinafter, this mixture is referred to as Resin R-1. Refractive index of the resin R-1 is 1.357, _{T g} was 90 ° C..

In the same manner as described above, the polymer and the additive were melt mixed to produce a uniform mixture. The obtained mixture was named Resin R-2 to Resin R-15, and the composition, refractive index, and T _g (° C.) are shown in Table 1 including Resin R-1. In Table 1, “amount of additive” represents the ratio (mass%) of the additive in the mixture. The additives used are as follows.

CFE: A chlorotrifluoroethylene oligomer having an average molecular weight of 2000.
PPE: Perfluoropolyether having an average molecular weight of 4000 (trade name “Fomblin Z03” manufactured by Augmont).

[Fiber creation example]
In the example in which the following SI type optical fiber was produced, the numerical aperture (NA) of the obtained SI type optical fiber was measured by the far field pattern method (based on JIS-C6862). Moreover, the transmission loss measured the transmission loss in wavelength 500-1600nm by the cutback method. The fiber was produced by the following two methods.

Preform method: Polymer (or resin) to be clad is melt-molded at 250 ° C. to produce a cylindrical tube, and polymer (or resin) to be core is melt-molded at 250 ° C. A cylinder having a slightly smaller outer diameter is produced. A cylindrical body is inserted into the hollow portion of the cylindrical tube, heated to 230 ° C. and combined to produce a preform, and the preform is melt-spun at 250 ° C. to obtain an SI type optical fiber.
Double-layer extrusion spinning method: Using an extruder, a polymer (or resin) as a core is placed in the center and a polymer (or resin) as a clad is placed in the outer periphery, and concentrically at 250 ° C. An SI type optical fiber is obtained by extrusion spinning.

(Example 44)
By the preform method, an SI type optical fiber having a core of polymer P-1 and a cladding of polymer P-10, an outer diameter of 1000 μm, and a core diameter of 980 μm was obtained. The measurement result of the transmission loss of the obtained SI type optical fiber is shown in FIG. As shown in FIG. 1, the transmission loss of this SI-type optical fiber is 62 dB / km at 650 nm, 20 dB / km at 850 nm, and 22 dB / km at 1300 nm, so that light from visible light to near infrared light is excellent. It was an optical fiber that could be transmitted. The NA was 0.34. When this SI type optical fiber was stored in an oven at 70 ° C. for 5000 hours and then subjected to a heat resistance test for re-measuring transmission loss, no change was observed and the heat resistance was good.

(Examples 45-56)
In the same manner as in Example 44, an SI type optical fiber was produced by the preform method. Table 2 shows the types of core and clad materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI type optical fiber. Further, when a heat resistance test was performed under the same conditions as in Example 44, no transmission loss was observed in any SI type optical fiber, and the heat resistance was good.

(Example 57)
An SI-type optical fiber having a clad of resin R-12 and a core of polymer P-1, an outer diameter of 1000 μm, and a core diameter of 900 μm was obtained by a two-layer extrusion spinning method. The optical transmission loss of this SI type optical fiber is 146 dB / km at 650 nm, 85 dB / km at 850 nm, 71 dB / km at 1300 nm, and is an optical fiber that can transmit light from visible light to near infrared light well. It was. The NA was 0.35. When this optical fiber was stored in an oven at 80 ° C. for 3000 hours and then subjected to a heat resistance test for re-measurement of transmission loss, no change was observed and the heat resistance was good.

(Examples 58 to 70)
In the same manner as in Example 44, an SI type optical fiber was produced by the preform method. Table 3 shows the types of core and clad materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI type optical fiber. Further, when a heat resistance test was performed under the same conditions as in Example 44, no transmission loss was observed in any SI type optical fiber, and the heat resistance was good.

(Examples 71 to 80)
In the same manner as in Example 44, an SI type optical fiber was produced by the preform method. Table 4 shows the types of core and clad materials, outer diameter and core diameter, transmission loss, and NA of the obtained SI type optical fiber. Further, when a heat resistance test was performed under the same conditions as in Example 44, no transmission loss was observed in any SI type optical fiber, and the heat resistance was good.

(Example 81)
By a two-layer extrusion spinning method, an SI type optical fiber having a core of resin R-8 and a cladding of resin R-12, an outer diameter of 1000 μm, and a core diameter of 950 μm was obtained. The optical transmission loss of this SI type optical fiber is 146 dB / km at 650 nm, 85 dB / km at 850 nm, 71 dB / km at 1300 nm, and is an optical fiber that can transmit light from visible light to near infrared light well. It was. The NA was 0.58. When the heat resistance test was performed under the same conditions as in Example 57, the transmission loss did not change and the heat resistance was good.

42 is a graph showing the transmission loss (wavelength: 500 to 1600 nm) of the SI type optical fiber of Example 43.

Claims (21)

The core is made of an amorphous fluororesin (A-1) composed of a fluorine-containing polymer having substantially no hydrogen atom and having a chlorine atom in the side chain, and the cladding contains substantially no hydrogen atom. A step index type plastic optical fiber comprising an amorphous fluororesin (B) composed of a fluoropolymer and having a refractive index difference between a core and a clad of 0.020 or more. A fluorine-containing polymer constituting the amorphous fluororesin (A-1) is a polymer having a repeating unit represented by the following formula (1) and having a repeating unit obtained by cyclopolymerization of a monomer (a-1) having a chlorine atom. Or a repeating unit in which the monomer (a) represented by the following formula (1) is cyclopolymerized and a repeating unit in which the monomer (c) represented by the following formula (2) is polymerized. The step index type plastic optical fiber according to claim 1, which is a polymer.
However, m and n are each independently an integer of 0 to 5, and R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a perfluoroalkyl having 1 to 9 carbon atoms. Represents a group, a chlorine atom or a fluorine atom.

The fluorine-containing polymer constituting the amorphous fluororesin (B) is a polymer having a repeating unit obtained by polymerizing the monomer (b) represented by the following formula (3). Step index type plastic optical fiber as described.
However, R < ¹¹ > and R < ¹² > represent a C1-C9 perfluoroalkyl group or a fluorine atom each independently.

The step index type plastic optical fiber according to claim 1, 2 or 3, wherein the amorphous fluororesin (B) contains a fluorine-containing plasticizer having substantially no hydrogen atom. The core is made of an amorphous fluororesin (A) composed of a fluoropolymer containing a high refractive index agent and substantially free of hydrogen atoms, and the clad is substantially free of hydrogen atoms. A step index type plastic optical fiber comprising an amorphous fluororesin (B) made of a polymer and having a refractive index difference between a core and a clad of 0.020 or more. The fluorine-containing polymer constituting the amorphous fluororesin (A) is a polymer having a repeating unit obtained by cyclopolymerizing the monomer (a) represented by the following formula (1): Step index type plastic optical fiber as described.
However, m represents an integer of 0 to 5, and R ¹ , R ² , R ³ and R ⁴ each independently represents a C 1-9 perfluoroalkyl group, a chlorine atom or a fluorine atom.

The step index type plastic optical fiber according to claim 5 or 6, wherein the high refractive index agent is a fluorine-containing aromatic compound having substantially no hydrogen atom. The fluorine-containing polymer constituting the amorphous fluororesin (B) is a polymer having a repeating unit obtained by polymerizing the monomer (b) represented by the following formula (3): The step index type plastic optical fiber according to 7.
However, R < ¹¹ > and R < ¹² > represent a C1-C9 perfluoroalkyl group or a fluorine atom each independently.

The step index type plastic optical fiber according to claim 5, 6, 7 or 8, wherein the amorphous fluororesin (B) contains a fluorine-containing plasticizer having substantially no hydrogen atom. The core is made of an amorphous fluororesin (A) composed of a fluoropolymer having substantially no hydrogen atom, or the amorphous fluororesin (A) containing a high refractive index agent, and the cladding is substantially It is made of an amorphous fluororesin (B-2) composed of a fluorine-containing polymer having a refractive index of less than 1.300 having no hydrogen atom, and the refractive index difference between the core and the clad is 0.020 or more. A step index type plastic optical fiber. The fluoropolymer constituting the amorphous fluororesin (A) is a polymer represented by the following formula (1) and having a repeating unit obtained by cyclopolymerizing the monomer (a). Step index type plastic optical fiber.
However, m represents an integer of 0 to 5, and R ¹ , R ² , R ³ and R ⁴ each independently represents a C 1-9 perfluoroalkyl group, a chlorine atom or a fluorine atom.

The step index type plastic optical fiber according to claim 10 or 11, wherein the high refractive index agent is a fluorine-containing aromatic compound substantially having no hydrogen atom. The fluoropolymer constituting the amorphous fluororesin (B-2) has a repeating unit obtained by polymerizing the monomer (b-1) represented by the following formula (4) and has a refractive index of 1. The step index type plastic optical fiber according to claim 10, 11 or 12, which is a fluoropolymer of less than 300.
However, R ¹³ is a perfluoroalkyl group having 2 to 9 carbon atoms, R ¹⁴ represents a perfluoroalkyl group or a fluorine atom having 1 to 9 carbon atoms.

The step index type plastic optical fiber according to claim 10, 11, 12, or 13, wherein the amorphous fluororesin (B-2) contains a fluorine-containing plasticizer having substantially no hydrogen atom. The core contains an amorphous fluororesin (A) or a high refractive index agent composed of a fluoropolymer having a repeating unit represented by the following formula (1) and having the cyclopolymerized monomer (a) Amorphous fluororesin comprising the amorphous fluororesin (A) and a clad having a repeating unit obtained by polymerizing the monomer (b-1) represented by the following formula (4) (B-3) or the amorphous fluororesin (B-3) containing a fluorine-containing plasticizer having substantially no hydrogen atom, wherein the refractive index difference between the core and the clad is 0.020 or more. Step index type plastic optical fiber.
However, m is an integer of 0-5, R < ¹ >, R < ² >, R < ³ > and R < ⁴ > are each independently a C1-C9 perfluoroalkyl group, a chlorine atom or a fluorine atom, R < ¹³ > is C2-C9 A perfluoroalkyl group, R ¹⁴ represents a C 1-9 perfluoroalkyl group or a fluorine atom.

The core is made of an amorphous fluororesin (A) composed of a fluoropolymer having substantially no hydrogen atom, or the amorphous fluororesin (A) containing a high refractive index agent, and the cladding is substantially An amorphous fluororesin (B) composed of a fluorine-containing polymer having no hydrogen atom or an amorphous fluororesin (B) containing a fluorine-containing plasticizer having substantially no hydrogen atom, A step index type plastic optical fiber having a number (NA) of 0.415 or more. Perfluoro (2-pentyl-1,3-dioxole). A fluorine-containing polymer having a repeating unit obtained by polymerizing perfluoro (2-pentyl-1,3-dioxole) as a monomer. An optical member comprising a fluoropolymer having a repeating unit obtained by polymerizing perfluoro (2-pentyl-1,3-dioxole) as a monomer. The optical member according to claim 19, wherein the optical member is a plastic optical fiber. 21. The optical member according to claim 20, wherein a fluoropolymer having a repeating unit in which perfluoro (2-pentyl-1,3-dioxole) is polymerized as a monomer is used as the core or cladding of the plastic optical fiber.

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